"We are not interested in a change for change's sake exercise. The first thing we've got to satisfy ourselves is that proposed changes will deliver the policy outcome you want - stronger economic growth, while at the same time being fair and not increasing the overall tax take."

"If they pass that test, then as practical politicians we've got to ask ourselves: will the public go for it? Can we build enough support to get there? But at this stage we have not made a decision."

Mr Morrison said if the proposal to increase the GST was knocked back he would find other ways to cut income tax.

"My objective in this role will be to wherever I can reduce the tax burden on people who are working hard and running businesses. Now, on every occasion circumstances may not allow it. You can't part the Red Sea on everything, but where I can, people should know, that's my focus."

He was unlikely to move against the negative gearing tax concession that allows landlords to write off losses on rental income against other income including wages.

"Negative gearing has been and continues to be a real opportunity for middle income earning Australians," he said. "Nurses and doctors and policeman or others, these are people working every day and trying to get ahead, they're not the problem."

Opposition Leader Bill Shorten said the only reason the government backtracked on the GST was panic among Liberal backbenchers about losing their jobs.

"If the Liberals think they can get away with a 15 per cent GST on everything, they will do it," he said. "I know what a Liberal government will do if they are re-elected at the next election. The 15 per cent GST will be back on the table."

On Sunday Mr Turnbull walked away from talk of a GST-for-income-tax swap, saying it would have to deliver strong benefits to growth and jobs that was "worth the trouble and expense of making the change".